I have recently found this on ebay:
Item Number: 280515794086
It is a listing of 15 helmets and 10 caps, I thought I would share it with you all as there seems to be some very collectable pieces in it, including a city of london helmet & a london and north easten helmet!
It is quite hard to find because if you type in police helemet you cant find it because helmet has been spelt wrong in the title!!!
Hope this helps and good luck to any of you that bid!